WO1996011783A1 - Methods for and machines for use in the lining of pipelines and passageways - Google Patents

Abstract

The machine disclosed is a cylindrical body made up of thin segment shaped, radially arranged magnets (32, 34) which establish magnetic fields. The magnetic fields (33, 35) are arranged either directly or by distributor/commutator means to extend radially. By rotation of the magnets or the commutator the radial fields can be caused to reverse at high frequency and this alternating high frequency energy is used to activate the lining tube through which the machine is passed.

Description

Methods for and Machines for Use in the Lining of Pipelines and Passageways

This invention relates to methods of and machines for use in the lining of pipelines and passageways, especially those •pipelines or passageways which are located underground.

Such methods make use of tubular linings which are moved into the pipelines or passageways and are positioned on the pipeline or passage surface to line same. In the present invention such linings are either (i) flexible tubes of a material which can be and is impregnated with a curable synthetic resin on of which the resin is cured after the tube is placed on the pipeline or passageway surface to form on same a rigid cured resin lining pipe inside the pipeline or passageway, which acts as a host pipe; or (ii) a rigid tube of thermoplastic material which can be softened when in the pipeline or passageway, then shaped by fluid pressure to conform to the pipeline or passageway surface and then cooled to re-rigidify and form a rigid lining pipe inside the pipeline or passageway which again acts as a host pipe.

Hereinafter, the pipeline or passageway will be referred to as the host pipe.

The present invention is concerned with lining tubes which need to be "activated". That is, they need to be changed in some way so that they can perform their final function and the present invention is concerned with "activating" the lining tube after it is inside the host pipe for, in the case of the resin impregnated tube curing or initiating the cure of the resin, and, in the case of the thermoplastic tube heating the tube to soften same. To perform this activation, energy having high frequency wave reversals is used. It is now well known and well established (see U.S. Patents 4009063 and 4064211) that underground sewer passageways can be rehabilitated by a relining operation which involves the use of a tubular structure impregnated with a curable synthetic resin. The structure is introduced by any of various means into the passageway and is held by fluid pressure so as to be "inflated" against the passageway surface typically by water (water inflation) or air (air inflation) and whilst it is so held the resin impregnating the absorbent material of the lining cures or is caused to cure so that there results a hard, rigid lining pipe lying on the passageway surface. This lining pipe prevents ingress and egress of fluids to and from the passageway, enhancing its operation. Long lengths of lining pipe can be applied in this way, and an entire art of softuning or "cured in place" lining as it is alternately known, has been established.

The basic idea is outlined in U.S. patents Nos 4009063 and 4064211, and in the latter patent the method disclosed is a turning inside out of the lining by water and this process has become known as "water eversion" . When air is used it is called "air eversion".

Conventionally, in order to perform a softlining operation, the tubular structure is manufactured using absorbent textile material, in particular a needled felt, and that felt is then impregnated with the curable synthetic resin. This manufacture and impregnation conventionally takes place under factory conditions, and the lining is then transported to site where it is positioned on the passageway surface and inflated and then the resin is cured by the application of heat. As soon as the resin has been mixed (it usually includes a resin matrix and catalyst and/or accelerator) it has a finite life referred to as the "pot life", during which it will remain uncured. With the passage of time curing takes place automatically. It is therefore important that as soon as the resin has been mixed to impregnate the lining, the installer should take the lining to site and insert it in as short a time as possible. The pressure on the installer to act quickly after mixing creates disadvantages, an obvious one of which is that if the installation for some reason is delayed after the mixing, there is a risk that curing will take place before the lining has been inserted, in which case the lining is wasted. Curing can also take place when the lining is partially installed which creates even greater problems. To prevent premature cure, the impregnated linings are often packed in ice as they are transported to site.

Because of these difficulties, attention has been directed to providing a "quiescent" or "latent" resin system which will remain in the uncured state for a substantial length of time, for example up to a year, after mixing, but can be initiated by the application of some external influence such as light radiation, ultrasonics, induction heating, and the like. Efforts to achieve such a quiescent system have however not met with much success compared to the use of the conventional heat cure resin.

In one specific method of providing a quiescent system as described in European Patent Application No 0551790, a resin formulation is provided which is relatively quiescent, but it includes a quantity of particles which are electrically conductive and/or magnetically permeable such particles being for example of ferro magnetic material or ferri magnetic material (e.g. iron, ferrite typically manganese and/or zinc ferrite) which acts as an activator for the resin when a magnetic field is applied thereto. The magnetic field action induces (i) eddy currents in the particulate material and these currents, due to the electrical resistance of the material produce heat which in turn initiates and/or effects the cure of the resin, or (ii) hysteresis losses in the particulate material, especially at the higher frequencies of the magnetic field, which produces the heat generated; or combined effects may be produced.

In a preferred case, the resin will include a curing catalyst and/or accelerator (initiator) which is held in the resin so as to be isolated from the resin matrix. For example, it may be held in microcapsules or in adsorbent particles. When the heat is generated by the application of the magnetic field, the catalyst accelerator and/or initiator is released causing the curing of the resin to commence and to be completed.

In order to produce an appropriate high frequency magnetic field, an electric induction coil or coils is/are located inside the pipeline or passageway with its axis/their axes lying longitudinally of the passageway whilst the lining is held to the passageway surface. The induction coil, when one is provided, preferably should lie as close as possible to the lining material so that when a high frequency (radio frequency - RF) electric current is applied to the coil, an alternating magnetic field is established which passes through the lining material in its plane, and alternates with the alternating electrical supply, producing said eddy currents and/or hysteresis losses in the particulate material, with the effect as discussed above.

Difficulties arise in connection with the use of RF electrical supplies underground such as to make it not feasible. The difficulties include but are not restricted to the following:-

1. A linear power amplifier is needed to generate an alternating flux underground, and this leads to low efficiency typically in the order of 60%. Transister circuits capable of producing 40 kW dissipation, needed for an output of 100 kW, are not readily available. Switching techniques could be used to provide some efficiency, but these are expensive to implement and involve the use of very high currents. For example even at 1000 volts, a current of 100 amps would have to be switched at 200 kHz. These figures could be even higher when coil losses are taken into account. Impedance conversion would inevitably be required, which would involve the use of a transformer. Management of the heat generated by the drive electronics would constitute an insoluble problem even in the case where a water inflation method is used and circulation of cooling water is possible.

2. Accommodating the high power circuit in a small size suitable for introducing into an underground pipeline would be extremely difficult.

3. Arrangements would necessarily be complex and would therefore be expensive. It would be difficult to service and different designs would be needed to suit different pipe sizes and different power requirements.

4. The efficiency of an induction coil is low.

5. As linings may be of a length in the order of 500 meters, there would be a substantial distance between the radio frequency power source to drive the coil and the coil itself, and a long transmission line would be needed. Such a transmission line would be a coaxial cable in order to avoid reflection and standing waves from occuring on the cable, because such waves could prevent the free flow of the radio frequency power. At a typical 50 ohm impedance, very high voltages in the order of 2200 volts at 100 kW power would be required, which could create very dangerous conditions inside the pipeline or passageway especially if water is used (as is usual) as the fluid for inflating the lining.

6. The conductors of the coil would require to be cooled, which would present a considerable problem having regard to the high magnetic field strengths (and consequently high currents) needed to cross any gap between the armature and the lining. Such gap may in fact be filled with water where water is used for the inflation of the lining. When air inflation is used, the apparatus would overheat.

7. As the load impedance is variable (depends upon pipe size, lining thickness etc) it is difficult using RF power to compensate for this variation from ground level.

8. The system has intrinsic safety problems.

9. Because of the low efficiency, high power generators would be required.

The abovementioned disadvantages also apply to a greater or lesser extent even when the power source and system operate at lower frequencies under the RF range.

The present invention seeks to provide an activation method whereby the aforesaid disadvantages or problems are obviated or mitigated.

In accordance with the invention in one aspect, the means for providing the induction heating comprises a rotary assembly including magnets, preferably permanent magnets of north and south poles arranged by the rotation to create an alternating magnetic field extending between the poles and which intersects the lining. Although the invention could be applied using electromagnets which would involve taking electrical supplies to the magnets, best advantage is achieved using permanent magnets.

The advantage of permanent magnets is that it is possible to eliminate any electrical supply or connections inside the pipeline or passageway, because the rotor can be driven by a non-electrical power source, such as a hydraulic motor.

In one preferred arrangement, the permanent magnets are arranged in alternating north south configuration in a direction circumferentially of the rotor. This means that the magnetic field flux lines lie in planes transverse to the rotor axis so that the flux lines of the magnetic field will loop outwardly in extending from each pole to the adjacent pole.

The magnets may be in the form for example of wedge shaped segments which are arranged face to face to make up the rotor. They may however be of any shape decided upon after design optimisation to give required field shape and density.

In one case the rotor rotates and by mechanically rotating the rotor, so the lining will be subjected at each location to alternating magnetic fields providing the same conductive heating effect as described above, it being mentioned that either the resin material in the lining will preferably be provided with said particulate material which is responsive to the alternating magnetic field applied to the lining to generate eddy currents in the particulate material and/or to generate hysteresis losses in the lining, or where the lining is applied to a host pipe of electrically or magnetically permeable material such as cast iron, the particulate material may not be necessary. The induction apparatus could be contained in a non magnetic material chamber which could be sealed so that it could be operated under water, and the only moving parts apart from the fluid drive would be the rotor and the bearings. The non magnetic material preferably is of plastic, but other materials could be used.

Inductive heat generation is proportional to the frequency of magnetic field reversals, and therefore it is preferable that the maximum number of poles be provided on the rotor although there will obviously be a practical limit. Secondly, it is desirable that the rotor should be rotated at as great a speed as possible, and therefore it might be desirable to use a high speed turbine as the driving force. In this connection it may be preferable to provide special high speed bearings such as gas or magnetic bearings and indeed the high speed operation could be enhanced if the unit were mounted in an evacuated or low pressure enclosure.

It is preferable that the magnets be of the high energy type (e.g. Neodymium based) to achieve high flux density in the lining.

In an alternative arrangement, the magnets are arranged on the rotor so that each magnet defines an north pole and a south pole, but the south poles are located radially inwardly of the north poles, or vice versa, so that the flux lines will extend from the inner south poles radially outwardly between adjacent north poles, and will then loop back to the north poles, the looped portion of the magnetic field intersecting the lining. In this arrangement, the respective magnetic fields as they radiate outwardly from the inner south poles will be mutually repulsed, which enhances shaping of the magnetic field and ensures that a maximum amount of flux radiates usefully outwards to intersect the lining. Additionally, in this arrangement, more poles can be mounted on the rotor, which in turn permits the generation of much higher frequencies with rotation of the rotor. This arrangement also enhances the capability of the equipment to operate on a bigger range of pipe sizes and a bigger range of lining thicknesses.

Using this alternative arrangement, and by way of example, the field reversal frequency which can be obtained in the lining and/or in the host pipe, is equal to the rotational speed times the number of magnets on the rotor and for example with a 50 magnet rotor operating at 2,000 rpm, a flux reversal frequency of 16.7 kHz could be achieved. It is believed furthermore, that a rotor speed of up to 100,000 rpm is readily attainable, which would give an output flux reversal frequency of 83 kHz.

It is to be mentioned that rotors of the type described with over one hundred poles are routinely used in high power stepping motor applications and therefore there should be no difficulty in providing an appropriate rotor design. At such an operating frequency, and if driven to saturation, irons and various steels exhibit very high eddy current losses and to avoid potential chemical compatibility problems with the resin, the particles when provided could be coated with a protective coating such as PTFE before the particles are mixed with the resin. It is also to be mentioned that non ferrous materials such as ferrite materials, brass and stainless steel could also be used either as an alternative or in conjunction with the previously mentioned particles.

The invention also applies to a method of curing resin especially a resin impregnating a lining tube using the apparatus as aforesaid, the resin if necessary including the said particulate material, and microencapsulated catalyst accelerator and/or initiator.

In a variation of the method, where the linings are applied to the interior of pipes which are electrically or magnetically conductive material such as cast iron, the pipe may in itself form the heating element by providing that the magnetic flux passes therethrough. If the pipe is electrically conductive heat will be generated by the "short circuited generator windings" mode of operation. If they are magnetically permeable, eddy and hysteresis losses will dominate.

As an alternative, or additionally, the apparatus can be used for heating and curing a resin which is provided with an additive which lowers the bulk resistivity of the resin. Such an additive could be carbon particles, and in this case when the system is operational, it would be equivalent to an electrical generator, with the generated current running through the additive material in the resin.

The basic apparatus may resemble a commercial flywheel energy storage unit, and it is to be pointed out that in this field there is much expertise concerning high rotational speed assemblies and low loss bearings of which use could be made in the final design and construction of the apparatus according to the invention.

The apparatus and method described have a number of advantages including the following.

1. The apparatus and method are simple and reliable.

2. The apparatus provides high power output.

3. The apparatus does not require the use of any electrical components in the pipeline or passageway and therefore it has intrinsic safety.

4. There are no electrical transmission problems such as occur with the transmission of AC especially RF power.

5. It can be high powered in that non electrical drives which are available can be up to 250hp and the use of these power units such as water pumps, air compressors or hydraulic power packs and hosing present no particular safety or logistical problems as far as use is concerned.

6. The apparatus does not require any special cooling as there will be negligible losses in the magnets and little loss in the bearings. The use of fluid to drive the power unit intrinsically provides cooling for the power unit.

In the case where a thermoplastic pipe embodying the magnetically permeable particles such as disclosed in International Patent Application No WO 92/20198 is involved, the passage of the machine through the pipe causes softening of the pipe which can then be inflated up onto a surface to be lined, and afterwards the expanded pipe is cooled to remain in position on said surface.

The present invention in another embodiment comprises a machine with magnets to define the magnetic fields which in use will intersect the lining, and the magnets are carried by a stator and rotary commutator means is used to distribute the magnetic fields to for example stationary distributor finger means which are arranged so as to be locatable on in close proximity to the inside of the lining tube.

By providing the magnets on a stator and rotating the commutating means, so the lining will be subjected in a kinetically efficient manner at each location to alternating magnetic fields providing the conductive heating effect as described above, it being mentioned that either the resin material in the lining will preferably be provided with said particulate material which is responsive to the alternating magnetic field applied to the lining to generate eddy currents in the particulate material and/or to generate hysteresis losses in the lining, or where the lining is applied to a host pipe of electrically or magnetically permeable material such as cast iron, the particulate material may not be necessary.

By the use of spring fingers as the distributor means, the arrangement also enhances the capability of the equipment to operate on a bigger range of pipe sizes and a bigger range of lining thicknesses.

The invention in another aspect also has application where the lining tube is activated by the application thereto of ultrasonic energy. The lining tube is impregnated with synthetic resin and the resin may be made special by formulating the resin so that after mixing the catalyst, resin matrix and accelerator (if provided) it will remain uncured until the ultrasonic energy is applied, but a more usual method is to embody the catalyst and/or accelerator in microcapsules as described for example in International Patent Application No. GB93/00107 so that the catalyst and/or accelerator is kept out of contact with the resin matrix until the microcapsules are broken and the catalyst and/or accelerator is/are released into the matrix to commence the cure of the resin.

The use of ultrasonic energy to rupture the capsules provides the advantage that the initiation of the curing of the resins can be under close control by the installer, which is highly desirable, for the reasons given above. Indeed, the installer by this arrangement now can impregnate his linings when he wishes and store them, impregnated, to be used in the future. A certain degree of standardisation can therefore be effected adding to the efficiency of the process.

As to the equipment for applying the ultrasonic energy, an appropriate generator is pulled through the passageway after the lining has been applied thereto, and this method has the advantage that it is not necessary to use hot water. Ultrasonic energy can furthermore be applied through gases and liquids and there is no need to use a gas for inflating the lining.

Conventional ultrasonic generators use electrical transducers, but due to problems in achieivng the required levels of power output, only small samples of impregnated lining material have been cured satisfactorily.

In one proposal, an ultrasonic generator is driven by an ultrasonic electrical source of high power at ground level which drives an ultrasonic generator when inside the underground passageway having the lining inflated against its surface. The generator generates ultrasonic waves which propagate along the axial direction of the passageway and impinge upon a reflector ahead of the generator whereby the waves are prevented from travelling down the passageway and are reflected in a radially outwards direction to be targeted and impinge upon the lining to cause high frequency mechanical agitation in the resin, which in turn causes the micro capsules to disintigrate and so release the catalyst and/or accelerator; conventional curing can then take place.

The generator of the ultrasonic vibrations as described is similar to generation of audio sound from an audible generator, except for the reflector. Ultrasonic generators do however operate above the audible range e.g. >20Khz.

This system has a number of drawbacks including the followingi-

1) The delivery of high power along the cable (which can be 500m long) connecting the power source and generator requires high voltage to minimize power loss in the cable, but these high voltages are potentially dangerous.

2) The power source, because of its high power, would be expensive, inefficent and difficult to design.

3) Because of the high power needed the generator would need to be very large; it may not fit into the passasgeway.

4) The transducers (electromagnetic and piezoelectric) are not particularly efficient and would be prone to overheating.

The combination of the above drawbacks would frustrate the scaling up of a laboratory unit into one for field service. Therefore, there is the desirability of using ultrasonic energy for curing specially formulated resins, as considerable advantages can be achieved thereby but the equipment for effecting the cure of items such as linings on pipeline and passageway surfaces by using ultrasonic energy is not available, especially having regard to the facts that underground passageways are relatively inaccessible and contain hostile environments (dark, wet, non-man entry in many cases) .

This aspect of the invention is concerned with an apparatus for the generation of vibration energy especially ultrasonic energy whereby appropriately formulated resins can be selectively cured and in particular the apparatus is usable for curing tubular linings having resin absorbent material which is impregnated with the tubular linings having resin absorbent material which is impregnated with the formulated resin, especially when said linings are held by fluid pressure on passageway surfaces.

According to this aspect of the invention an apparatus for creating vibration energy comprises first and second sets of north and south magnets arranged alternately, the sets being relatively moveable so that the magents are alternately attracted and repelled for setting up vibrations useable to cure appropriately formulated resins.

The sets of magnets preferably comprise a first set mounted for rotation about an axis and a second set arranged around the first set and mounted for resilient and limited radial movement to produce said vibrations.

The magnets of the second set may be plates of m gnetisable material or they may be permanent magnets, mounted on a flexible support sleeve, whilst the magnets of the first set preferably are permanent magnets (they could be electro magnets) of wedge shape arranged face to face to form a rotor, the active surface of which comprises alternating north and south poles. The first set of magnets preferably is carried on a rotor shaft which is driveable by a high power drive unit connected thereto.

By virtue of this construction, a unit is provided which can be moved through a passageway lined by a lining impregnated with an appropriately formulated resin system e.g. one with a microencapsulated catalyst, and whilst it is so moved the rotor is rotated at high speed, vibrating the magnets of the second set to produce vibrations (typically at ultrasonic frequencies i.e. >20Khz) which are transmitted by the fluid (usually water or air) for the passageway which holds the lining inflated.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, wherein;-

Fig. 1 is a diagrammatic side elevation showing in section how the machine in the present invention is used;

Fig. 2 is an end view of an induction coil inside an underground passageway for the curing of a resin impregnated liner which lines the passageway;

Fig. 3 is a sectional elevation of the arrangement shown in Fig. 2;

Fig. 4 is an enlarged sectional detail view of the lining;

Fig. 5 is a view similar to Fig. 1 showing an embodiment of the invention;

Figs. 6 and 7 are respectively similar views of an apparatus according to the embodiment of the present invention of Fig. 5 and operating according to the method of the invention, the views respectively showing the apparatus in two different conditions of operation;

Fig. 8 is a view similar to Fig. 5 showing a fragment of the rotor, and a magnet arrangement according to an alternative embodiment of the invention;

Fig. 9 is a view similar to Fig. 6 but of the arrangement shown in Fig. 8; Fig. 10 is a diagrammatic cut away view showing how optical cables can be used for heat sensing with advantageous effect;

Figs. 11 and 12 are an end view and a perspective view of an apparatus according to another embodiment of the invention;

Figs. 13 and 14 are graphs showing the relationship between specific power loss against peak flux density at various different frequencies in respect of iron powder and ferrite;

Fig. 15 is a sectional elevation of the machine when shown in position inside a lining tube in a pipeline or passageway, the section being taken on the line D-D of Fig. 16;

Fig. 16 is an end elevation of the machine shown in Fig. 15;

Figs. 17, 18 and 19 are sectional elevations taken on the lines A-A, B-B, and C-C in Fig. 15 respectively;

Fig. 20 is an end view of the machine shown in Fig. 15 but taken from the opposite end from that shown in Fig. 16;

Figs. 21, 22 and 23 are developed views of the commutating arrangement in order to illustrate how the machine functions;

Fig. 24 is a diagrammatic representation of a prior proposed system using electromagnetic ultrasonic transducer; and

Figs. 25 and 26 are illustrative views showing the operation of the apparatus according to another embodiment of the present invention.

Referring to the drawings, and firstly to Fig. 1, in this figure there is shown an underground passageway 10X such as a sewer extending between a pair of manholes 12X and 14X leading from the sewer to ground level. A lining tube 16X is being applied to the sewer between manholes 12X and 14X, and the figure shows a machine 18X which is passing through the interior of the tube 16X by being pulled therethrough by means of a winch 2OX to which is connected a pull rope 22X. Rope 22X is led over guide pulleys 24X at the top of manhole 14X and 26X at the bottom of manhole 14X. The end of the rope 22X is connected to an eye 28X at the front end of the machine 18X.

To the rear end of the machine is connected a compressed air hose 30X which receives air under pressure from a compressor 32X. The trailing end of the lining 16X is closed by a cap 34X so that the interior 36X can be pressurised by supply of compressed air from hose 30X through an outlet 38X. A regulating valve 40X controls the supply of compressed air through the line 42X to an air motor 46X at the rear of the machine 18X in order to drive the rotary assembly of the machine as will be hereinafter described.

Basically, the tube 16X may be a resin impregnated tube such as is used in a cured in place lining system and it contains magnetically permeable particles which are activated by the machine 18X as it travels along the tube in the direction of arrow 40X. This activation of the particles can either be used to heat the resin in order to cure same, or it can be used for example to fracture microcapsules or absorbent particles which contain catalyst for the resin in order to release that catalyst which in turn causes curing of the resin. The air under pressure in the tube as indicated by reference 36X holds the tube against the surface of the passageway 10X and therefore as and when curing takes place, the tube will become hard and will remain in position lining the passageway. There are various techniques for inserting the tube 16X which are known from the art and will not be described herein and indeed the construction and content of the tube is not in essence in this invention except insofar as the magnetic fields produced by the machine 18X must cause eddy current and hysteresis loss reaction in the magnetically permeable material in order to generate heat which in turn is used for the curing of the resin in tube 16X.

As alternative the tube 16X may in fact be a thermoplastic tube which is rigid, but as the machine 18X is pulled therethrough and as the magnetic fields are applied to the tube, so magnetically permeable particles in the tube are caused to heat up which in turn softens the tube and it can be expanded again by pressurizing space 36X to cause it to lie on the surface of the sewer 10X until such times as the plastics material has cooled down in the enlarged diameter and remains on the surface of sewer 10X.

Referring now to Figs. 2 to 4 which show a previously proposed method for the curing of a resin impregnated liner tube, reference numeral 10 indicates an underground sewer, to which is applied by fluid pressure a lining tube 12 of a construction shown in greater detail in Fig. 4. The lining tube 12 is, it is to be assumed, in a flexible condition, and it comprises a material of a textile nature which is impregnated with a curable synthetic resin (assumed to be in the uncured condition) .

Whilst the lining is so held by fluid pressure, an induction coil 14 of a size roughly matching the inner diameter of the lining tube is pulled through the lining tube 12. The induction coil 14 is supplied with high frequency (RF) electrical power which may be of RF or less frequency so as to create an alternating high frequency magnetic field 16 which as shown in Figs. 2 and 3 penetrates the lining 12 for the purposes, as explained hereinbefore, of creating eddy currents in electrically conductive and/or magnetic particles in the lining tube 12 and/or generating hysteresis losses in these particles so as to create a heating effect, the heat in turn serving to cure the resin as described hereinbefore which impregnates the lining tube 12.

It will be understood that although in Figs. 2 and 3 the flux direction is shown by the arrow heads, this represents only one half cycle of the alternating field, and the magnetic field will be in the opposite direction in the other half of the cycle.

Referring to Fig. 4, the lining tube 12 in fact comprises a relatively thick layer or layers 12A of a synthetic felt material, typically polyester fibre felt on one side of which is coated an impermeable membrane 12B so that the pressurizing fluid will be kept out of contact with the felt layer or layers 12 .

Reference numeral 18 represents a number of the individual fibres of the felt shown by way of example, and reference numeral 20 indicates the magnetic particles which are excited by the field 16 which penetrates the thickness of the lining.

Numeral 21 shows microcapsules containing catalyst.

The generated heat causes the microcapsule shells to melt which in turn releases the catalyst which cures the resin so that the lining will turn into a hard rigid lining pipe on the surface of the sewer 10. The above described arrangment is set forth in European Patent Application No 0551790.

One embodiment of the present invention is illustrated in Figures 5 to 7, and the present invention provides the same curing result as hereinbefore described insofar as the resin is again provided with the magnetic particles 20, and a magnetic field is passed through the lining to excite the particles to cause same to have eddy currents and hysteresis losses created therein which generates the heat sufficient to perform the curing, but in accordance with the embodiment of the invention shown in Figs. 5 to 7, the magnetic field is provided by permanent magnets, with the consequent advantages as hereinbefore described.

As shown in Figs. 5, 6 and 7, a plurality of magnets which are wedge shaped are arranged in face to face relationship so as to form a rotor 30. The magnets alternate north 32 and south 34, and are carried by a rotor shaft 36. The shaft 36 is shown as being connected to be driven by a fluid motor 38 (such as a turbine or air motor) to which hydraulic driving fluid can be supplied through go and return lines 40 and 42 which for example extend to ground level. To achieve high rotational speed, a speed increasing gearbox could be used which would enable the achievement of an acceptably high rotor speed from a standard low speed hydraulic motor.

The adjacent magnets being of north and south poles create small fixed magnetic fluxes 33, 35 which loop between the magnets, and through the lining, but as will be appreciated and as shown best in Fig. 5, the magnetic fields of fluxes 33 alternate with and extend in the opposite direction in relation to fluxes 35. Therefore, as the rotor is rotated inside the sewer and inside the lining 12 as shown in Fig. 5 each part of the lining is subjected to a reversing magnetic field effect as described in relation to Figs. 2 to 4. The same curing effect is achieved without the disadvantages of using an electrical drive system as envisaged in Figs. 2 to 4, and the arrangement of Figs. 5 to 7 has the attendant advantages as hereinbefore described. The rotor 30 will be of a size matching as closely as possible to that of the inner diameter of the lining when applied to the sewer surface so as to provide a minimum air gap between the lining tube and the outer surface of the rotor but the unit has to be capable of being pulled through the lining to effect the cure of the resin of the lining throughout the length of the lining.

As the apparatus works in some cases in an underground passageway which contains a liquid, it is of advantage to provide that the liquid can pass through the apparatus especially along the central axis thereof. This enables in some circumstances, the liquid e.g. sewage which normally flows in the pipeline to continue flowing avoiding the need to "over pump" the said liquid. Over pumping is a process of diverting the liquid from the pipeline to ground level from a location upstream of the section of pipeline being lined to a location downstream of that section. T assist in passing the liquid through the apparatus, it may incorporate a pump which could be powered by the hydraulic motor 38. The pump may include an Archimedes screw forming the centre spindle of the apparatus and through which the liquid is pumped.

The centre of the apparatus may simply be defined by a hollow shaft for flow through, and as described hereinafter, that hollow shaft may be used to provide a special anti-friction bearing and the magnetising of same, the magnetic effect being used in conjunction with the magnets of the apparatus rotor.

As mentioned above, the gap between the magnets and the lining should be as small as possible and normally the magnets would be in a diameter approx 2/3rds of the diameter of the pipe being lined. Such arrangement provides sufficient clearance to enable the apparatus to move effectively along the pipeline and perform the curing function satisfactorily, but because this ratio is fairly important this could lead to different machines for pipes of different sizes, were it not for a further preferred feature according to the invention which is the provision of sizing sleeves to enable the variation in effective diameter of the machines. A machine designed to have say a 250 mm diameter could be converted to effective diameter of anything up to say 400 mm by inserting it into an appropriate sleeve. The sleeve comprises,preferably, non-magnetic material such as plastics and would be of cylindrical shape and of outside diameter to suit the pipe to be lined. Its inner diameter would be sized to accommodate the basic machine.

Preferably, each sizing sleeve incorporates magnetically permeable, insulated, radial, magnetic segments, for example of cobalt iron alloy, which effectively extend the magnetic field lines at to a larger diameter with no significant flux loss.

A range of machines of different sizes would probably still be required insofar as larger diameter pipes lined with thick linings would need appropriately sized rotor magnets and drive turbine.

The magnets 32, 34 of the rotor 30 as shown in Fig. 6 are axial and extend lengthwise of the shaft 36, but some additional advantage can be achieved by arranging for the magnets to extend spirally or helically of the rotor axis. By this step, particles suspended in the liquid around the rotor are prevented from taking hold on the rotor magnets or on the outside of the machine casing.

This gentle helix configuration of the magnets produces the effect during rotation of the magnets that the suspended magnetic particles in the liquid (magnetic rubbish) are swept axially of the apparatus, the direction of sweep depending upon the helix direction and the direction of rotation. Without the helical twisting of the magnets, the magnetic rubbish would tend to revolve around the apparatus continuously at a speed slower than that of the rotor (due to the friction of the particles) and large particles would stick to the apparatus and could distort the magnetic fields.

Another effect achieved by spiralling the magnets is that additional thrust on the apparatus can be achieved in the same way as thrust is achieved from a mechanical lead screw. This occurs due to the reaction force which arises from transferring heating energy into the pipe. That reaction, because of the twisting of the magnets has thrust as well as torque and the direction of that thrust depends upon the helix angle direction and the direction of rotation.

The apparatus illustrated in Figs. 5 to 7 can be constructed with any of the features hereinbefore set forth and the apparatus can be operated in accordance with any of the method steps hereinbefore set forth.

In the arrangement of Figs. 5 to 7, there can be a short coming that as more poles are added in order to increase the alternating magnetic field frequency (to liberate more energy in the lining) there is a corresponding reduction in the pitching between poles. The shorter the distance between poles, the shorter the magnetic circuit between the poles, and this means that some of the flux may pass directly through the space between the lining and the poles, and will therefore not influence the curing of the lining. One way of dealing with this difficulty would be to increase the rotor size so that it is a closer fit to the lining, but there is a limit on rotor size, as some clearance must be maintained to allow the rotor to rotate on the one hand, and secondly to allow the apparatus as it is moved through the pipe to negotiate bends and pipe joints and the like. Accordingly, with the arrangement of Figs. 5 to 7 it may be necessary to provide different sized units for different pipe sizes, but this difficulty may be overcome by the embodiment of the invention illustrated in Figs. 8 and 9 which continues to allow the generation of high frequencies.

As shown in Fig. 8, the magnets 50 are radially arranged, but each magnet 50 has north and south poles. In the arrangement described, the north poles are at the radially outward end of the magnet, whilst the south poles are at the radially inward end. With this arrangement, the magnets 50 can be closely packed together, and the lines of flux as shown are forced through the gaps between the magnets. The lines of flux lie to opposite sides of each magnet, and therefore the loops of flux indicated by references 52 and 54 alternate in direction, flux 52 alternating with flux 54. As the rotor is rotated therefore, these loops 52 and 54 will intersect linings lying at quite a considerable spacing from the magnets 50. Because the flux lines flow in smooth curves, they form a field shape as shown with the loops 52 and 54 being forced outwards because the parallel fluxes between the magnets are in fact mutually repulsed.

When such an arrangement is operated in conjunction with a lining, the flux lines will be shunted or forced into the lining thickness by the host pipe, if that host pipe is of a low permeability material such as clay, which is common. If the pipe is on the other hand of a magnetically permeable material such as cast iron, the flux lines will travel through the pipe, but will heat it causing the same curing effect as is achieved with the use of particulate material in the lining.

As explained, each magnet generates both a forward and reverse magnetic field 52 and 54 having regard to the position of the lining, so that upon rotation of the magnets by driving of the rotor, the field reversal effect will take place as described herebefore.

Fig. 9 is a view similar to Fig. 6, but shows the magnetic arrangement of Fig. 8. Similar reference numerals have been used for those parts already described in relation to Fig. 6 so that further description is not necessary.

The magnet shown in Figs. 8 and 9 are shown as discrete magnets, but they could be fabricated by a construction method using a single tubular magnet which is bonded to the spindle and then axial grooves are cut in the tubular magnet to provide the individual magnetic segments. These segments as shown in Fig. 9 are wedge shaped, but they could be shaped in any way that enhances magnetic field shape.

The particular arrangement shown in Figs. 8 and 9 has a number of advantages over the embodiment of Figs. 5 to 7 in that it allows a greater number of poles to achieve a higher frequency at the same speed of revolution of the spindle; it allows a greater gap length between the poles and the lining for increased usability and versatility; and it allows better shaping of the magnetic fields.

In each embodiment, the unit which is traversed along the inside of the pipeline with the lining applied thereto may be encased in a plastic casing in order to isolate it from the surrounding water when water inflation is used.

As heat is generated for the purposes of effecting the cure of the resin, it may be desirable to provide for regulation of the temperature inside the pipeline, because the temperature could become uncontrolled if the apparatus was simply drawn through the pipe at some predetermined speed based upon average conditions. The rate of heat transfer varies depending upon a number of factors including ground temperature, water temperature (water inflation) lining thickness, and where provided the distribution of inductive particles. In the cases where the original pipe acts as the heat source, when the heating mode arises because of the bulk resistivity of the pipe, the heating effect will depend upon the state of the pipe i.e. whether or not it is corroded, and whether or not it has cracks or the like. Heating in such circumstances could be quite random.

One method for providing for heating regulation is to control by curie temperature regulation. To this end, when ferrite particulate material rather than iron powder is used, the advantage is achieved that such materials have a low curie temperature, and therefore the temperature to which the lining can be heated is automatically controlled. The curie temperature is the temperature at which magnetic materials loose all their magnetic properties and their relative permeability falls from a high value to almost zero. In the case of some ferrites, this change takes place over only a few degrees rise in temperature. Different grades of ferrites can be selected with curie temperatures of between 120°C to 300°C. Therefore, the use of ferrite as the heat generating particulate material would mean that the system could self-regulate in temperature, because as soon as the ferrite reaches its curie temperature it becomes non-magnetic meaning that it liberates no more heat as a result in the changing flux. Ferrite materials do have a major drawback which is cost in that they are expensive. However, ferrite materials can be used for the heat regulation advantage which is achieved and discussed above.

If the ferrite is dispersed very thinly throughout the resin in order to save costs, and the curie temperature regulation is employed, there could be a situation that not enough power would be liberated in order to effect a fast enough cure of the resin.

However, if it is economic to use the required amount of low curie temperature ferrite, sensing of the temperature of any section of the lining can be effected by monitoring the fluid pressure to the drive motor 38. Thus, if the ferrite material in a section of the lining has reached the curie temperature, this would be indicated by a reduction in take off power of the fluid motor as the ferrite switches off at the curie temperature. This reduction in power would be accompanied by a pressure drop in the feed line to the motor, and this signal could be used to regulate the speed of progression of the equipment along a pipe. A system of heat regulation is therefore achieved.

Another method of monitoring the heating effect comprises an infra-red sensing method.

Iron, both cast iron and iron powder work to very high temperatures without any curie type effects. Because of this the curie method mentioned above cannot be adopted. The use of iron powder is however attractive in that it is substantially lower cost than ferrite, and it has a much higher unit heat loss than ferrite. With the use of iron powder therefore the lining will continue to heat with no automatic temperature control such as is achieved by the use of curie materials. The heating up can however be monitored and controlled by examining the infra-red radiation coming from the lining section as it warms up. A suggested method of doing this is to use fibre optics. Fibre optics in the form of cables could be used to form a sensing array by having ends along the length and around the diameter of the casing housing the apparatus, for example is shown diagrammatically in Fig.10. Such an arrangement provides a three-dimensional view of the "hotness" of the lining section surrounding the apparatus. Referring to Fig. 10, the apparatus casing is indicated by reference numeral 60, and the fibre optic cables by reference 62. These cables have ends as indicated at 64 in the casing 60 and the ends look radially outwards at the surrounding lining. The cables are led back to a CCD chip camera grid 66, the camera being infra-red sensitive. Reference numeral 68 represents the video cable connecting the CCD chip to ground level.

Each fibre 62 conducts only the electromagnetic radiation to a single pixel on the CCD array device 66 which preferably is housed in a magnetically inactive and isolated part of the apparatus. The video output of the device 66 could be transmitted to a TV screen above ground with possible computer generation of a suitably modified geometry image. Thereby, either a human operator or a computer control system could monitor the output of the fibre optic cables and control the rotational speed of the fluid motor 38 and/or the speed it travels through the pipe to achieve a controlled, multistep cure.

Depending upon the signals outputted, a control loop could be provided based on this system of sensing which is thermomapping, to adjust the position of the apparatus in relation to the centre line of the pipe to cater for thermovariations circumferentially of the lining. The output power could therefore be directed to arcuate lengths of the lining to ensure even curing. For example even in a case where the underground pipe lies in the ground water table such that the water table lies half way up the pipe, the output power could be particularly directed to those sectors which experience cooling on the water table. For the worst irregularities, the apparatus could be designed deliberately under size and could be designed to be driven for example along a continually circular path around the pipe axis, with one side of the unit at any time outputting most of the power. This would allow highly precise, targetted and control curing of every part of the lining.

The use of optical fibres as described above, which fibres may be of glass or plastic polymer, provides the advantage that the fibres would not interact with the magnetic induction fields. There should be relatively little adsorption of the infra-red radiation in the water when water inflation is used because of the short distances from the lining to the apparatus housing. In any event, it is frequency information which provides the temperature indication, and the frequency should not be effected by signals passing through the water.

The use of fibre optics is preferred to electronic sensors, because with electronic sensors, induced currents could give false readings, and they could distort the magnetic fields. In the present arrangement, the equipment runs completely cold and there is no interference from either very hot induction coils or from the surrounding water.

As regards the running conditions for the equipment of the present invention, it is more important to have a greater flux density than it is to have a high frequency, because the losses in the materials which create the heat are proportional to frequency only on a substantially linear basis, whereas these losses are proportionate to the square of flux density. It is more important therefore to maintain high flux density and fortunately this is easier to achieve than higher frequency. With the appropriate use of permanent electromagnets, the condition of a superconducting flux may be achieved. The embodiment of Figs. 8 and 9 lends itself to the production of a high flux density in the lining.

The apparatus may be propelled through the pipeline in any suitable manner, such as by the use of towing cables, but another advantage can be achieved if a fluid power drive system is used in that if the outlet is allowed to discharge directly into the pipe, it can provide in effect a jet thrust for the apparatus to cause it to be propelled along the pipe. For example a 100 kW water based unit under no load would be equivalent to having a 130 horsepower outboard motor operated to drive it down the pipe. The inlet hose 40 being full of water would be neutrally buoyant where water inflation is used and it will offer little if any resistance to the forward movement of the apparatus. With this arrangement only access to one end of the apparatus and indeed access to one end of the lining is needed, which means that linings having one end sealed which are used in so-called "blind shot ends" applications can be cured. With this arrangement only a single hold back rope would be needed to control the infeed of the apparatus, and it could be used at the end of the curing operation to pull the apparatus back along the lined pipe.

In operation, the apparatus will in fact be subject to a fairly large torque which will tend to rotate the whole apparatus and its housing. To counter this effect, the means for holding the apparatus in the pipe must be appropriately designed or alternatively there could be dual and contra rotating magnet systems to nullify the torque effect. Fingers or arms may be provided to keep the apparatus central of the pipe as it moves therealong. Another and advantageous embodiment of the invention is shown in Figs. 11 and 12. These figures show an apparatus for use in the same fashion as the apparatus already described in relation to the earlier figures. In the arrangement shown in Figs. 11 and 12, the apparatus comprises a hollow central core sleeve 70 which is of a magnetisable material and indeed is magnetised so as to define a plurality of similar poles, in this case south poles, on the outer surface, and the opposite poles, in this case north poles, along the inside surface. The rotor 72 is also sleeve-like, and is formed with a number of permanent magnets 74 between which are axially slots 76. The magnets 74 have in this case outer surface north poles and inner surface south poles so that the inner surface south poles face the south poles on the core sleeve 70. This means that the repulsion between the opposing south poles on the magnet 74 and the sleeve 70 create a magnetic bearing between the sleeve 72 and the sleeve 70 which will be frictionless in nature as there will be no contact between the respective sleeves. Thus, the central sleeve 70 can be stationarily mounted whilst the sleeve 72 is free to rotate. Rotation is achieved by means of a water nozzle 78 from which issues a jet 80 of water which in turn impinges upon driving buckets 82 fixedly connected to the sleeve 74. In the arrangement shown in Fig. 11, the sleeve 72 is adapted to be driven in anti-clockwise direction, and it would be appreciated that the buckets 82 are disposed around the entire circumference of the sleeve 72.

The magnetic fields which serve to cure the lining are generated in a similar manner to that illustrated in Figure 7, and two are indicated by reference numeral 84.

The apparatus is shown in Fig. 11 as having an outer stationary cover sleeve 86 of the construction hereinbefore described.

Operation of the apparatus from the description of Fig. 11 will be understood insofar as the water nozzle with the jet of water 80 drives the buckets 82 which in turn rotates the sleeve 72 at high speed. The bearing support from the sleeve is provided by the magnetic repulsion between the fixed sleeve 70 and the sleeve 72, and the magnetic fields 84 will intersect the lining and cause heating of the magnetically susceptible particles which in turn causes curing of the synthetic resin in the lining.

Fig. 12 shows that for the balancing of the rotation reaction torque, two sections 88 and 90 may be provided in that the rotating sleeve 72A of the section 88 is adapted to be rotated in the opposite direction from rotating sleeve section 72B, and the water nozzle 78A is arranged to have its jet 80A impinge on the buckets 82A so as to drive the section 88 anti-clockwise, whilst the nozzle 80B is arranged to be of opposite hand and the buckets 82B face in the opposite direction so that jet 80B impinges the buckets 82B to drive the section 90 in a clockwise direction.

An advantage of the arrangement described is that the hollow centre 92 allows a flow of the liquid through the apparatus as described hereinbefore, and restriction to flow can be made as low as possible. Provision of a magnetic bearing means no bearing wear and the magnetic repulsion has the effect of providing a better shape to the magnetic fields 84 for the intended purposes.

It may be desirable to provide a centrifugal water shield in order to prevent the water jets from entering the rotating magnet assembly. Figure 12 illustrates graphically the feature mentioned herein that it is preferable for the magnets to be shaped to conform to a gentle helical curve. In Fig. 12, the magnets of the respective sections are indicated by the reference numeral 74A and 74B, whilst the axial slots are indicated by the references 76A and 76B.

It will be appreciated that any of the structural features described herein and the operation steps of the respective embodiments can be adapted for any of the other embodiments.

Figs. 13 and 14 are included to show the relationship between flux density and power losses for iron powder (Fig. 13), and a ferrite 3C85 (Fig. 12). These graphs which are logarithmic plots show that there is a linear arrangement between power losses and frequency, but also that the power losses increase sharply with increased flux density.

Figures 15 to 23 show another embodiment of the invention, wherein the magnets are carried by a stationary cylindrical body and commutators are used for magnetic field distribution, which has the advantages hereinbefore referred to, and referring to these figures, the machine comprises a main shaft 110 which is supported for rotation in bearings 112, 114. The shaft receives its drive and rotates in use by virtue of carrying an impeller 116 which is driven by low pressure fluid which in fact fills the inside of the lining tube 118 and passes from the right hand end of the assembly through the path indicated by arrows over the impeller plastes, and exits from the left hand end of the machine shown in Fig. 15. The shaft 110 carries a pair of bushes 120, 122 on which are mounted commutator members 124 and 126, the function and purpose of which will be explained hereinafter. The described components comprise the rotary part of the machine. The remainder of the machine is stationary, and it is adapted to be pulled through the interior of the lining tube 118 by means of a clevis eye 128 to which a suitable pulling rope will be attached. It can be appreciated that the machine moves from left to right in the figure as it performs its operation.

The purpose of the commutator members 124 and 126 is to distribute an alternating magnetic field through a pair of distributor rings 130 and 132 of a suitable magnetically permeable material whereby the alternating magnetic field will pass from the peripheries of the rings 130 and 132 outwardly and along through the material of the lining tube 118.

The magnetic field is established by a plurality of magnetic plate segments 136, each of which is generally U-shaped as shown in Fig. 15, and comprises three sections 136A, 136B and 136C which are connected together in order to define alternate north and south poles at the faces which are opposed to the commutator members 124 and 126.

The operation of the machine, which will be explained in more detail in relation to Figs. 21, 22 and 23, provides that as the shaft 110 and the commutator members 124 and 126 carried thereby are rotated, so the magnetic fields established by the magnets 136 cause the distribution rings 130 and 132 to become alternately magnetically charged north and south poles, and for an axially extending, alternating magnetic field to be set up in the thickness of the lining 118. As explained hereinbefore, this alternating magnetic field causes particles in the lining to be magnetically activated and to heat up which has the effect of softening the lining if it is of a thermoplastic material to enable it to be expanded onto the surface of the pipeline or passageway to be lined, or of effecting curing of a synthetic resin where the lining tube is one which is impregnated with a synthetic resin containing the said particles.

This description is however mainly concerned with the construction and operation of the machine.

The clevis eye 128 is carried by an end collar 140 which is bolted to a support sleeve 142, the end collar 140 and sleeve 142 having in registration axial apertures to allow the passage of the driving fluid therethrough as indicated by the arrows.

The collar 142 supports a flexible seal member 144 which is in the form of a ring having a flanged end which bears against the inner surface of the lining in order to form a pressure seal to ensure that upstream of the clevis pin 128 a sufficient pressure will be established to cause the driving fluid to flow through the machine to drive the impeller 116.

The cap 140 receives in a central boss thereof the centre of a fixing ring 146, to which the distribution ring 132 is attached by means of bolts 148. These bolts 148 extend between the magnets 136 and anchor to the distribution ring 130 at the other end of the magnet assembly, and the bolts also anchor an end cap 150 at the other end of the machine.

At said other end, there is a support ring 152 which supports the distribution ring 130. Rings 146 and 152 preferably are of magnetically insulating material in order to ensure that the magnetic flux will not be lost through the end of the machine, and will be directed outwardly of the distribution rings 130 and 132 as described hereinbefore.

As shown in Figs. 16 to 20 the various rings are appropriately apertured to allow the flow of driving fluid, which typically will be air, through the machine.

As can be seen from Fig. 18 the magnets 136 are radially arranged, and are separated by magnetically insulating filler segments 154.

Figs. 21, 22 and 23 are useful in explaining the functioning of the machine and the arrangement of the commutating members 124 and 126.

As shown in these figures, which are developed views, the magnets 136 which are permanent magnets, have their north and south poles arranged in alternating configuration. Thus, if it is assumed that the first magnet as shown in Figs. 21 has its north pole at the left hand end of the machine and its south pole at the right hand end, the next magnet has its south pole end at the left hand end of the machine, with the north pole at the right hand end of the machine and so on.

The commutation members are in the form of bridge elements 160 which in the example shown are arranged in staggered pairs at opposite ends of the magnets so that each bridge element 160 bridges a pair of magnet ends, and taking the four bridge pieces together, they link five magnets to provide a continuous magnetic path of sinuous form. The fingers 162 on collector strips 164 are arranged to form the pick-up points for the ends of these magnetic paths, and these fingers are arranged as shown so that in any particular magnetically conducting condition, there will be magnets 136X which are isolated or neutralised.

Fig. 21 shows the commutator in a position in which the left hand collector strip 164 is a south pole and the right hand collector strip 164 is a north pole. The magnetic field therefore in Fig. 21 will be such that the distributor ring 130 is the south pole of the magnetic field, and the distributor ring 132 is the north pole.

The strip 164 and the bridge member 160 are carried by the shaft 110, and they move relative to the magnets 136 which remain stationary. Fig. 22 shows a position when the commutators 124 and 126 have moved relative to the magnets, but have not yet reached the alternate position when the left hand collector strip 164 becomes a north pole and the right hand becomes a south pole. This condition is shown in Fig. 23 which is the position when the commutator has moved one magnetic pole pitch relative to the magnets 136. The diagrams are self explanatory insofar as the magnetic field between the strips 164 has now reversed and therefore the magnetic field through the lining tube will have reversed. It will be understood that the commutator members pass the magnets at high speed and therefore there will be high speed magnetic field fluctuation to achieve the effect as described hereinbefore.

The bridge member 160 may be located under the north and south poles of the magnets as shown in Fig. 15, whilst the collector strip 164 may be located in radial alignment with the inner ends of the distribution discs 130 and 132.

The present machine provides an excellent construction for providing the alternating magnetic field required to achieve activation of the magnetic particles in the lining tube and has all of the advantages herein set forth.

The machine is pulled progressively through the lining tube so that the particles will be progressively activated, in order to complete the lining operation. Another embodiment of the invention, which makes us of vibration set up using a rotor of magnets, similar to the rotor of Fig. 6 or 8, is shown in Figs 25 and 26, whilst Fig. 24 shows a prior proposal for comparison with Figs. 25 and 26.

The arrangement shown in Fig. 24 is that hereinbefore described, in which a lining material 210 of resin absorbent material and impregnated with a specially formulated resin including a microencapsulated catalyst is held against the surface of an underground pipeline by fluid pressure, applied for example by air or water.

Above ground is an ultrasonic electrical power source 212 which is connected to an ultrasonic generator 214 inside the lining underground, the generator 214 embodying an ultrasonic transducer of the electromagnetic or piezo electric type.

Long and robust cables 216 connect the power source of the generator.

In the example illustrated, the generator is arranged to generate ultrasonic waves in the medium which pressurises and inflates the liner, such waves as indicated by reference 218 being generated so as to propogate along the axis of the underground passageway. The waves however impinge upon a reflector 220 which causes the waves to be directed radially outwardly as shown at 222 with the effect that the sonic waves or vibrations are caused to impinge upon the liner 10 in a radial direction. This generates the high frequency mechanical agitation in the resin, which in turn causes the microcapsules to disintegrate whereby the catalyst contained therein is released. The release of the catalyst into the resin mix causes conventional curing of the resin to take place so that the lining 10 becomes a hard rigid lining pipe on the passageway surface.

The travelling waves and the vibrations generated are at a frequency range above the upper frequency audible to humans, and therefore are at a range greater than >20Khz.

The arrangement described in Fig. 24 suffers however from the disadvantages hereinbefore indicated.

Figs. 25 and 26 show an embodiment of the present invention whereby sets of magnets are used in order to generate vibrations.

As shown in Figs. 25 and 26, a first set of permanent magnets defining north and south poles define a rotor 230 which is rotatable about an axis defined by a drive shaft 232 by which a fluid motor 234 is connected to the rotor 230. Shaft 232 in use as shown lies along the axis of the pipeline or passageway, and the fluid motor casing supports a rigid steel housing 236 for a purpose to be explained.

As shown clearly the rotor 230 is made up of alternating north and south poles which are of wedge shape, and they are arranged to lie face to face so that north and south poles alter circumferentially around the outer surface of the rotor. Although not shown, the shaft 232 extends beyond the right-hand end of the rotor 230 and supports on a bearing another housing similar to housing 236, again for a purpose to be explained.

The magnets of the first set of magnets of rotor 230 are permanent magnets, but they could be electromagnets in other embodiments of the invention.

The second set of magnets comprises a series of curved plates, which may be of magnetic material as opposed to being permanent magnets, although permanent magnets are preferred. These curved plates together make up a continuous ring surrounding the rotor 230, and the angle subtended by each plate is equal to the angle subtended by each of the wedge shaped magnets of the rotor 230, or a slightly less angle so that there will be gaps between the magnet plates of a second set of magnets as shown in Fig. 25.

The second set of magnets have alternate south and north poles as shown and the ring defined by these magnets is concentric with the axis of the rotor 230.

Rotation of the rotor 230 causes the magnets of the second set alternately to be attracted and repulsed by the rotor magnets as the rotor is rotated. Fig. 25 shows the plate magnets of the second set in the repulsed condition, where like poles of the first set face like poles of the second set. Fig. 26 shows the condition in which the outer second set of magnets is attracted to the rotor magnets and opposite poles lie opposite.

As the rotor rotates, so the second set of magnets is oscillated in a radial direction, at a frequency determined by the number of poles on the rotor and the speed of rotation of the rotor. These frequencies can be up to ultrasonic.

The use of a fluid motor to drive shaft 232 is preferred as it will not be necessary to bring any electrical supply into the underground passageway. This is particularly important where the inflating fluid is water. It is preferred that water be the inflating fluid for the transmission of the vibrations from the plate magnets of the second set radially outwardly as shown by reference 236 onto the lining 10 to cause curing of the resin in the same manner as herebefore described in relation to Fig. 24.

The second set of magnets is mounted on an outer flexible housing material 240 which is in the form of a flexible sleeve having its ends anchored by flexible joints to the housings 236 at the left and right hand ends of the apparatus. This enables the set of magnets to oscillate evenly and radially to produce the vibrations. Sleeve 240 preferably is of flexible plastics material.

It is not necessary to have the same number of magnets in the second set as in the first set, but it is desirable that they occupy only one radial angular position each.

With the rotation of the motor, so the magnets of the second set are oscillated back and forth in a radial direction expanding and contracting the flexible sleeve 240, generating high levels of sound energy with minimum losses. The energy is generated in a radial plane to ensure that all of the energy is utilised in impinging upon the lining material for effecting the cure of the resin. The entire lining is cured by progressively moving the apparatus of Figs. 25 and 26 through the lining.

To achieve ultrasonic operation which means operating at a frequency of over >20 Khz, a 100 pole magnet rotor operating at 24,000 rpm is required. Rotors with over 100 poles are routinely used in high power stepping motor applications, and there is no technical hurdle in producing such a rotor driveable at the speed involved.

Fluid motor 234 may be a water turbine or an air or hydraulic motor.

The apparatus described in relation to Figs 25 and 26 has a number of advantages as used in the field of liner curing in pipeline applications including the following.

1. It is simple and relaiable.

2. It provides high power output.

3. It does not require any electrical components in the specific embodiment described and therefore it is intrinsically safe.

4. It does not suffer from problems associated with high power signal generation and transmission.

5. It can be readily constructed as high power (250 hp) water pumps, air compressors and hydraulic power packs are readily available as is high flow, high pressure hosing.

6. It does not present any cooling problems.

The apparatus will of course be designed to fit as neatly as possible into the lining consistent with the apparatus performing its function, because the smaller the distance which the generator has to transmit vibrations through the surrounding fluid, the better.

Claims

1. A method of activating a lining tube placed in a host pipe comprising the steps of moving through the interior of the tube on apparatus comprising a cylindrical body made up of circumferentially arranged magnets and either (i) rotating the body to cause magnetic fields which link the magnets and extend radially thereof to apply high frequency cyclic energy to the lining tube to activate same, or to (ii) rotating a commutator means to cause alternating magnetic fields to be distributed from the magnets of the body to apply high frequency cyclic energy to the lining tube to activate same.

2. A method according to claim 1, wherein the magnets are permanent magnets.

3. A method according to claim 2, wherein the magnets are elongated and extend axially of the body.

4. A method according to claim 3, wherein the poles of the magnets are at the ends of same and the magnets are separated by spacers and are arranged so that the north and south poles alternate circumferentially at the ends of the body.

5. A method according to claim 4, wherein there are rotatable commutators having pick up bridge members which distribute the magnetic fields of the magnets to distribution rings which feed the magnetic fields to the lining tube on a high frequency reversing basis as the commutators are rotated.

6. A method according to claim 3 wherein the magnetic poles are at the outer edges of the magnets and the magnets form alternating magnetic field loops which extend radially and intersect the lining tube.

7. A method according to claim 6, wherein the magnets are spaced circumferentially and the outer edges have similar poles as do the inner edges so that the said magnetic fields loop to the inner edges through the spacers between magnets.

8. A method according to claim 6, wherein the magnets are arranged so that circumferentially the poles of the respective magnets alternate.

9. A method according to claim 6, 7 or 8, wherein the magnets of the body are surrounded by a second set of magnets carried by a means enabling the second set of magnets to activate radially as the body is rotated, and that vibration forms the means of applying cyclic energy to the lining tube to activate same.

10. A method according to any one of the preceding claims wherein the body or commutator is rotated by means of a prime mover driven by fluid (gas or liquid) under pressure.

11. A method according to claim 10, wherein the said fluid is also used to urge the lining against the host pipe.

12. A method according to any preceding claim, wherein the lining tube contains metallic particles which are heated by the applied high frequency energy.

13. A method according to any preceding claim wherein the host pipe is metallic and is heated by the applied high frequency energy.

14. A method according to any preceding claim, wherein the lining tube comprises a tube of resin absorbent material which is impregnated with synthetic resin.

15. A method according to claim 14, wherein the resin contains micro encapsulated catalyst and/or accelerator, which microcapsules are ruptured by the applied high frequency energy.

16. A method according to any of claims 1 to 13, wherein the lining tube is a thermoplastic tube.

17. Apparatus for use in activating a lining tube, comprising a cylindrical body made up of circumferentially arranged magnets establishing magnetic fields extending radially of the body, and means for rotating part of the apparatus to cause high frequency reversal of said radially arranged magnetic fields.

18. A method according to claim 17, wherein the magnets are permanent magnets.

19. A method according to claim 18, wherein the magnets are elongated and extend axially of the body.

20. A method according to claim 19, whreein the poles of the magnets are at the ends of same and the magnets are separated by spacers and are arranged so that the north and south poles alternate circumferentially at the ends of the body.

21. A method according to claim 20, wherein there are rotatable commutators having pick up bridge members which distribute the magnetic fields of the magnets to distribution rings which feed the magnetic fields to the lining tube on a high frequency reversing basis as the commutators are rotated.

22. A method according to claim 19 wherein the magnetic poles are at the outer edges of the magnets and the magnets form alternating magnetic field loops which extend radially and intersect the lining tube.

23. A method according to claim 22, wherein the magnets are spaced circumferentially and the outer edges have similar poles as do the inner edges so that the said magnetic fields loop to the inner edges through the spacers between magnets.

24. A method according to claim 22, wherein the magnets are arranged so that circumferentially the poles of the respective magnets alternate.

25. A method according to claim 22, 23 or 24 wherein the magnets of the body are surrounded by a second set of magnets carried by a means enabling the second set of magnets to obviate radially as the body is rotated, and that vibration forms the means of applying cyclic energy to the lining tube to activate same.

26. A method according to any one of the preceding claims wherein the body or commutator is rotated by means of a prime mover driven by fluid (gas or liquid) under pressure.

27. A method according to claim 26, wherein the said fluid is alos used to urge the lining against the host pipe.